To meet the demand for continuously increasing transmission capacity, high spectral-efficiency (SE) and high data-rate systems have been developed. Orthogonal frequency division multiplexing (OFDM) technologies or Nyquist pulse multiplexing, for example, provide solutions to encode digital data in reduced bandwidth with and increased SE. Compared with OFDM, however, Nyquist signal transmission has several unique advantages such as lower receiver bandwidth and lower peak-to-average power ratio. However, according to conventional systems and methods, high symbol-rate Nyquist signal generation is difficult, especially for signals with quasi-zero roll-off factors.